If you go up 1st or down 2nd Avenue in the upper half of Manhattan, the lights are synchronized at something like 27 mph, which makes for an adequate speed and disincentives speeding, it seems to me, since you're only going to hit a red light if you get out in front of the synchronicity.

Synchronized traffic lights are real common in Germany. I'm no traffic planner but I imagine there's no good reason not to do this, in principle.